these are only used in the encoder.
frames_since_golden / frames_till_alt_ref_frame -> VP[89]_COMP
Change-Id: Ie14a6f46987bced685ddb449b85dc261caba6dfe
These arrays have constant values (no any updates). Removing two
corresponding memcpy calls. Making a little cleanup in vp9_entropymode.h
as well: removing redundant 'extern' keyword and moving all function
declarations at the end.
Change-Id: Ia16b38b46aec2e2500f5df29c40a297ae241dede
Removing tile_rows and tile_columns from VP9Common, removing redundant
constants MIN_TILE_WIDTH and MAX_TILE_WIDTH, changing signature of
vp9_get_tile_n_bits.
Change-Id: I8ff3104a38179b2c6900df965c144c1d6f602267
this was never fleshed out in the context of VP8, for which it was
added. for VP9 it has no meaning.
Change-Id: Iba2ecc026d9e947067b96690245d337e51e26eff
Adding segmentation struct to vp9_seg_common.h. Struct members are from
macroblockd and VP9Common structs. Moving segmentation related constants
and enums to vp9_seg_common.h.
Change-Id: I23fabc33f11a359249f5f80d161daf569d02ec03
Total encoding time for first 50 frames of bus (speed 0) @ 1500kbps
goes 2min34.8 to 2min14.4, i.e. a 10.4% overall speedup. The code is
x86-64 only, it needs some minor modifications to be 32bit compatible,
because it uses 15 xmm registers, whereas 32bit only has 8.
Change-Id: I2df53770c2e850813ffa713e1a91b45b0082b904
This commit fixed the allowable partition types for bottom-right
corner blocks.
When a block has over half of its pixels as valid content in both
vertical and horizontal directions, allow all the four partition
types in the bit-stream. Otherwise, apply partition type constraints.
Change-Id: I2252e2de7125a8bfb1c824bf34299a13c81102e3
Remove the bilinear filter mode, and the no-loopfilter mode, and the
related vp9_setup_version() function.
Change-Id: I32311367812faf37863131df3af37d63d03973d7
Implements ability to signal and decode frames that are
encoded using only intra coding modes. Only the decode
side has been implemented here.
Change-Id: I53ac6a8d90422cd08ba389e5236e15b45f9e93de
Reduces TX_SIZE contexts to 2 for each kind. The code is
cleaner and there is hardly any performance difference with
more than two contexts.
Results: almost neutral
Change-Id: I17656bd6db76224ae2856adf882504560e7dbaa4
Made changes to the frame header to write the sync
code in the frame header for a non-displayable,
intra-only frame.
Extended reset_frame_context to 2-bits.
(Submitting on behalf of Dmitri)
Change-Id: Ie836ae0df9ed572fb4f08aabe9351a555c4f3b96
Adds coding of transform size within a frame by use of context
of transform sizes selected in left and above blocks.
Also incorporates code for generating stats.
TODO: generate and incorporate new default stats
Change-Id: I6a7af099f6ad61d448521d9a51167aedaf638ed6
Refactors mbskip coding to be compatible with coding of the rest of
the symbols. Adds forward/backward adaptation and removes a lot of
the legacy code.
Results:
fast50: +1.6%
derfraw300: +0.317%
Change-Id: I395a2976d15af044d3b8ded5acfa45f6f065f980
The partition types of blocks sitting on the frame boundary are
constrained by the block size and the position of each sub-block
relative to the frame. Hence we use truncated probability models
to handle the coding of such information.
100 frames run:
yt 0.138%
Change-Id: I85d9b45665c15280069c0234ea6f778af586d87d
Changes to the coding of transform sizes, along with forward
and backward probability updates.
Results:
derf300: +0.241%
Context based coding of transform sizes will be in a separate
patch.
Change-Id: I97241d60a926f014fee2de21fa4446ca56495756
Code intra/inter, then comp/single, then the ref frame selection.
Use contextualization for all steps. Don't code two past frames
in comp pred mode.
Change-Id: I4639a78cd5cccb283023265dbcc07898c3e7cf95
Split partition probabilities between keyframes and non-keyframes,
since they are fairly different. Also have per-blocksize interframe
y intramode probabilities, since these vary heavily between different
blocksizes.
Lastly, replace default probabilities for partitioning and intra modes
with new ones generated from current codec. Replace counts with actual
probabilities also.
Change-Id: I77ca996e25e4a28e03bdbc542f27a3e64ca1234f
Adds backward adaptation and differential forward updates of switchable
interpolation filter probabilities. Also adds some cosmetic cleanups
and minor fixes on mv_ref probabilities.
derfraw300: +0.353% (with most coming from switchable interp changes)
Change-Id: Ie2718be73528c945fd0d80cfd63ca2d9cb3032de
Added two flags to the frame header:
intra_only:
Signals that the frame is encoded using only INTRA
coding modes.
reset_frame_context:
Indicates that the coding context specified
in the frame header should be reset to default values before the
frame is encoded/decoded.
Change-Id: I182d46f1f84fb67a13c46ad767f246a38d7861a2
This patch checks at the frame level to see if the previous
mode info context can be used. This patch eliminates the
flag check that was done for every mode and removes another
check that was done prior to every vp9_find_mv_refs().
Change-Id: I9da5e18b7e7e28f8b1f90d527cad087073df2d73
Adding API to read/write uncompressed frame header bits (it is not final
yet). Separate functions to read/write uncompressed header. Moving
clr_type, error_resilient_mode, refresh_frame_context,
frame_parallel_decoding_mode, frame_context_idx from compressed partition
to uncompressed frame header.
Change-Id: Id3ed8a387980c652ae147549412f4ec24a0a5bd0
1. remove prediction mode conversion
2. unified bmode, same for key and non-key frame
3. set I4X4_PRED count for pdf to 0, as I4X4_PRED is no longer
coded ever. It is determined by ref_frame and block partition
Change-Id: If5b282957c24339b241acdb9f2afef85658fe47d
Also do per-partition motion vector referencing in <sb8x8 partitions,
and adjust mvref finding for sub8x8 partitions.
Change-Id: Id3ed1ed4d2a8910d11d327db6cc63b8eb79f941f
The API is not final yet and can be changed. Actual layout of
uncompressed frame part will be finalized later. Right now moving
clr_type, error_resilient_mode, refresh_frame_context,
frame_parallel_decoding_mode from first compressed partition to
uncompressed frame part.
Change-Id: I3afc5d4ea92c5a114f4c3d88f96858cccc15b76e
Cleans up the experiment. Actually uses reduced counts for backward
updates, and reduced number of probabilities in the context.
No change in bitstream when the experiment is on.
Between expt on and off:
derfraw300 is down only -0.062% (which is better than when expts
were run previously).
Change-Id: I55285a049a0c22810bdb42914212ab5a4f8521b5
This is a mostly-working implementation of an extra channel in the
bitstream. Configure with --enable-alpha to test. Notable TODOs:
- Add extra channel to all mismatch tests, PSNR, SSIM, etc
- Configurable subsampling
- Variable number of planes (currently always uses all 4)
- Loop filtering
- Per-plane lossless quantizer
- ARNR support
This implementation just uses the same contents as the Y channel
for the A channel, due to lack of content and general pain in
playing back 4 channel content. A later patch will use the actual
alpha channel passed in from outside the codec.
Change-Id: Ibf81f023b1c570bd84b3064e9b4b8ae52e087592
Move set_partition_seg_context_ to common file. Use consistent
context setup conditions for partition probability model update at
encoder and decoder.
Change-Id: I24b7ed3b1c48e3d2568191a46b70136b99b67b1a
Make framebuffer allocations according to the chroma subsamping
factors in use. A bit is placed in the raw part of the frame header for
each of the two subsampling factors. This will be moved in a future
commit to make them part of the TBD feature set bits, probably only set
on keyframes, etc.
Change-Id: I59ed38d3a3c0d4af3c7c277617de28d04a001853
Update and buffer left/above partition information context per 8x8
block. This allows to further enable recursive partition down to
4x4 block size, and hence deprecating I4X4_PRED and SPLITMV.
This commit also fixes a context buffer swap/restore issue in 32x32
partition type search. This gives 0.1% performance gain for derf/yt.
Will refactor the superblock partition type search into recursion
form.
Change-Id: Ib61975aca5f12b78d8018481d7fa1393d085689b
The number of reference buffers is extended to 8 and
a reference sign-bias added for the LAST_FRAME.
Whilst the number of reference buffers used by an
individual frame remains unchanged at 3, these may
now be selected from 8 possible buffers.
Change-Id: I2d247b9c1c2b3a339d6c9fac125e81ba373f75a7
Work-in-progress, not yet ready for review. TODO items:
- bitstream writing (encoder) and reading (decoder)
- decoder reconstruction
Change-Id: I5afb7284e7e0480847b47cd0097cb469433c9081
Moving common code from encoder and decoder to vp9_get_qindex function.
Also moving quant-related constants from vp9_onyxc_int.h to
vp9_quant_common.h.
Change-Id: I70c5bfbaa1c8bf00fde0bfc459d077f88b6d46c8
Output changes slightly because of a minor bug in (at least) the sb32x16
block2above tx16x16 tables that previously existed in vp9_blockd.c.
Change-Id: I624af28ac200a8322d64454cf05c79e9502968cc
Using ALLOWED_REFS_PER_FRAME constants instead of hard coded 3, replacing
memcpy with plain struct assignment.
Change-Id: Ibc86f5d175fcb3f3a3eddacf593525370f1f854c
Function set_mb_row() and set_mb_col() do similar work and are always
called together, this commit merged them into a single function for
clarity and easy maintainence. This was a TODO item.
Change-Id: I956bd9ed6afb8b2b0469b20fd8bc893b26f8a0f3
This commit enables selecting probability models for recursive block
partition information syntax, depending on its above/left partition
information, as well as the current block size. These conditional
probability models are reasonably stationary and consistent across
frames, hence the backward adaptive approach is used to maintain and
update the contextual models.
It achieves coding performance gains (on top of enabling rectangular
block sizes):
derf: 0.242%
yt: 0.391%
hd: 0.376%
stdhd: 0.645%
Change-Id: Ie513d9673337f0d27abd65fb566b711d0844ec2e
Adds an experiment that codes an end-of-orientation symbol
for every eligible zero encountered in scan order.
This cleans out various other sub-experiments that were part
of the origiinal patch, which will be later included if found
useful.
Results are slightly positive on all sets (0.1 - 0.2% range).
Change-Id: I57765c605fefc7fb9d1b57f1b356843602abefaf
For 1080 material, this buffer is currently 2,270,928 bytes. This patch swaps
ptrs instead of copying and uses the last show_frame flag instead of setting
the entire buffer to zero. For the test clip used, the decoder improved by up
to 1%.
Change-Id: I686825712ad56043e09ada9808dc489f875a6ce0
Enable recursive partition information coding from SB64X64 down to
MB16X16. The bit-stream syntax is now supporting rectangular block
sizes. It starts from SB64X64 and recursively describes the partition
type of the current block. If the partition type is PARTITION_NONE,
the block is coded as a single unit; if it is PARTITION_HORZ or
PARTITION_VERT, the block is segmented into two independently coded
rectangular units, with no further partition needed; otherwise, the
block is segmented into 4 square blocks. i.e., PARTITION_SPLIT case,
each can be potentially further partitioned.
Forward adaptive probability modeling is used for the partition
information coding, conditioned on the current block size.
Change-Id: I499365fb547839d555498e3bcc0387d8a3587d87
This flag was added to VP8 to allow a mode where MB-level skipping
was not allowed, saving a bit per mb. It was never used in practice,
and hasn't been tested in VP9, so remove it.
Change-Id: Id450ec6904c6d06c1919508e7efc52d05cde5631
This is work-in-progress, it implements multiple ARF
encoding behind an experimental flag.
It adds the ability to insert multiple ARF frames into a
single ARF group. This patch implements the reordering
of the coded frames, and implements a fixed-length coding
pattern. It applies a fixed quantizer strategy based on
where the frame is in the coding sequence.
Further work to modify the rate control strategy is
ongoing and will be submitted via a set of future patches.
In this first step, each ARF group is recursively
bisected and an ARF frame added at that position in the
sequence. The recursion continues until ARF frames are
within MIN_GF_INTERVAL frames.
The code sits behind the "multiple-arf" experimental
flag ("CONFIG_MULTIPLE_ARF"). The experimental flag
"oneshotq" ("CONFIG_ONESHOTQ") also needs to be enabled
for this patch to work correctly.
Change-Id: Ie473b05ebb43ac473c0cfb659b2b8042823085e2
Pearson correlation for above or left is significantly higher than for
previous-in-scan-order (absolute values depend on position in scan, but
in general, we gain about 0.1-0.2 by using either above or left; using
both basically just makes this even better). For eob branch skipping,
we continue to use the previous token in scan order.
This helps about 0.9% on derf after re-training on a limited data set.
Full re-training and results on larger-resolution clips are pending.
Note that this commit breaks trellis, so we can probably get further
gains out of it by fixing trellis at some later point.
Change-Id: Iead68e296fc3a105cca746b5e3da9555d6010cfe
Adds a per-frame, strength adjustable, in loop deringing filter. Uses
the existing vp9_post_proc_down_and_across 5 tap thresholded blur
code, with a brute force search for the threshold.
Results almost strictly positive on the YT HD set, either having no
effect or helping PSNR in the range of 1-3% (overall average 0.8%).
Results more mixed for the CIF set, (-0.5 min, 1.4 max, 0.1 avg).
This has an almost strictly negative impact to SSIM, so examining a
different filter or a more balanced search heuristic is in order.
Other test set results pending.
Change-Id: I5ca6ee8fe292dfa3f2eab7f65332423fa1710b58
Renaming Width to width, Height to height and Version to version in
several structs and function signatures.
Change-Id: I084c3f7e747cb2ce3345aff27a3dff9b13a87543
If the intended display size is different than the size the frame is
coded at, then send that size explicitly in the bitstream. Adds a new
bit to the frame header to indicate whether the extra size fields
are present.
Change-Id: I525c66f22d207efaf1e5f903c6a2a91b80245854
Adds probability updates for extra bits for the nzcs, code for
getting nzc stats, plus some minor cleanups and fixes.
Change-Id: If2814e7f04fb52f5025ad9f400f3e6c50a00b543
This patch revamps the entropy coding of coefficients to code first
a non-zero count per coded block and correspondingly remove the EOB
token from the token set.
STATUS:
Main encode/decode code achieving encode/decode sync - done.
Forward and backward probability updates to the nzcs - done.
Rd costing updates for nzcs - done.
Note: The dynamic progrmaming apporach used in trellis quantization
is not exactly compatible with nzcs. A suboptimal approach has been
used instead where branch costs are updated to account for changes
in the nzcs.
TODO:
Training the default probs/counts for nzcs
Change-Id: I951bc1e22f47885077a7453a09b0493daa77883d
Split macroblock and superblock tokenization and detokenization
functions and coefficient-related data structs so that the bitstream
layout and related code of superblock coefficients looks less like it's
a hack to fit macroblocks in superblocks.
In addition, unify chroma transform size selection from luma transform
size (i.e. always use the same size, as long as it fits the predictor);
in practice, this means 32x32 and 64x64 superblocks using the 16x16 luma
transform will now use the 16x16 (instead of the 8x8) chroma transform,
and 64x64 superblocks using the 32x32 luma transform will now use the
32x32 (instead of the 16x16) chroma transform.
Lastly, add a trellis optimize function for 32x32 transform blocks.
HD gains about 0.3%, STDHD about 0.15% and derf about 0.1%. There's
a few negative points here and there that I might want to analyze
a little closer.
Change-Id: Ibad7c3ddfe1acfc52771dfc27c03e9783e054430
This patch extends the previous support for using references of a
different resolution in ZEROMV mode to all inter prediction modes.
Subpixel based best-mv scoring is disabled when the reference frame
differs in resolution from the current frame.
Change-Id: Id4dc3e5e6692de98d9857fd56bfad3ac57e944ac
This patch allows coding frames using references of different
resolution, in ZEROMV mode. For compound prediction, either
reference may be scaled.
To test, I use the resize_test and enable WRITE_RECON_BUFFER
in vp9_onyxd_if.c. It's also useful to apply this patch to
test/i420_video_source.h:
--- a/test/i420_video_source.h
+++ b/test/i420_video_source.h
@@ -93,6 +93,7 @@ class I420VideoSource : public VideoSource {
virtual void FillFrame() {
// Read a frame from input_file.
+ if (frame_ != 3)
if (fread(img_->img_data, raw_sz_, 1, input_file_) == 0) {
limit_ = frame_;
}
This forces the frame that the resolution changes on to be coded
with no motion, only scaling, and improves the quality of the
result.
Change-Id: I1ee75d19a437ff801192f767fd02a36bcbd1d496
Since there is no Y2, these values are always zero. This changes the
bitstream results slightly, hence a separate commit.
Change-Id: I2f838f184341868f35113ec77ca89da53c4644e0
These allow sending partial bitstream packets over the network before
encoding a complete frame is completed, thus lowering end-to-end
latency. The tile-rows are not independent.
Change-Id: I99986595cbcbff9153e2a14f49b4aa7dee4768e2
This is after discussion with the hardware team. Update the unit test
to take these sizes into account. Split out some duplicate code into
a separate file so it can be shared.
Change-Id: I8311d11b0191d8bb37e8eb4ac962beb217e1bff5
This patch adds column-based tiling. The idea is to make each tile
independently decodable (after reading the common frame header) and
also independendly encodable (minus within-frame cost adjustments in
the RD loop) to speed-up hardware & software en/decoders if they used
multi-threading. Column-based tiling has the added advantage (over
other tiling methods) that it minimizes realtime use-case latency,
since all threads can start encoding data as soon as the first SB-row
worth of data is available to the encoder.
There is some test code that does random tile ordering in the decoder,
to confirm that each tile is indeed independently decodable from other
tiles in the same frame. At tile edges, all contexts assume default
values (i.e. 0, 0 motion vector, no coefficients, DC intra4x4 mode),
and motion vector search and ordering do not cross tiles in the same
frame.
t log
Tile independence is not maintained between frames ATM, i.e. tile 0 of
frame 1 is free to use motion vectors that point into any tile of frame
0. We support 1 (i.e. no tiling), 2 or 4 column-tiles.
The loopfilter crosses tile boundaries. I discussed this briefly with Aki
and he says that's OK. An in-loop loopfilter would need to do some sync
between tile threads, but that shouldn't be a big issue.
Resuls: with tiling disabled, we go up slightly because of improved edge
use in the intra4x4 prediction. With 2 tiles, we lose about ~1% on derf,
~0.35% on HD and ~0.55% on STD/HD. With 4 tiles, we lose another ~1.5%
on derf ~0.77% on HD and ~0.85% on STD/HD. Most of this loss is
concentrated in the low-bitrate end of clips, and most of it is because
of the loss of edges at tile boundaries and the resulting loss of intra
predictors.
TODO:
- more tiles (perhaps allow row-based tiling also, and max. 8 tiles)?
- maybe optionally (for EC purposes), motion vectors themselves
should not cross tile edges, or we should emulate such borders as
if they were off-frame, to limit error propagation to within one
tile only. This doesn't have to be the default behaviour but could
be an optional bitstream flag.
Change-Id: I5951c3a0742a767b20bc9fb5af685d9892c2c96f
Adds a flag to disable features that would inhibit frame parallel
decoding. This includes backward adaptation and MV sorting based
on search in ref frame buffer.
Also includes some minor clean-ups.
Change-Id: I434846717a47b7bcb244b37ea670c5cdf776f14d
Adds an error-resilient mode where frames can be continued
to be decoded even when there are errors (due to network losses)
on a prior frame. Specifically, backward updates are turned off
and probabilities of various symbols are reset to defaults at
the beginning of each frame. Further, the last frame's mvs are
not used for the mv reference list, and the sorting of the
initial list based on search on previous frames is turned off
as well.
Also adds a test where an arbitrary set of frames are skipped
from decoding to simulate errors. The test verifies (1) that if
the error frames are droppable - i.e. frame buffer updates have
been turned off - there are no mismatch errors for the remaining
frames after the error frames; and (2) if the error-frames are non
droppable, there are not only no decoding errors but the mismatch
PSNR between the decoder's version of the post-error frames and the
encoder's version is at least 20 dB.
Change-Id: Ie6e2bcd436b1e8643270356d3a930e8989ff52a5
This commit restores the quality lost when the buffer-to-buffer copy
logic was removed. Note that this is specific to the current use of
golden frames and will need rework when RTC functionality is added.
Change-Id: I7324a75acd96eafd9e0f9b8633d782e390d5dc21
Previously there were two frame coding contexts tracked, one for normal
frames and one for alt-ref frames. Generalize this by signalling the
context to use in the bitstream, rather than tieing it to the alt ref
refresh bit. Also increase the number of contexts available to 4, which
may be useful for temporal scalability.
Change-Id: I7b66daaddd55c535c20cd16713541fab182b1662
Remove lst_fb_idx, gld_fb_idx, alt_fb_idx, refresh_last_frame,
refresh_golden_frame, refresh_alt_ref_frame from common. Gold/Alt are
encode side conventions. From the decoder's perspective, we want to be
dealing with numbered references.
Updates to active_ref 2 signal mode context switches, vestigial from
refresh_alt_ref_frame. This needs some clean up to make sense with
increased numbers of reference frames, as well as reimplementing the
swapping of alt/golden which was previously done using the
buffer-to-buffer copy mechanism removed in an earlier commit.
Change-Id: I7334445158b7666f9295d2a2dd22aa03f4485f58
Do reference counting the same way on the encoder as the decoder does,
rather than maintaining the 'flags' member of YV12_BUFFER_CONFIG.
Change-Id: I91dc210ffca081acaf9d5c09a06e7461b3c3139c
This is the first in a series of commits to add additional reference
frames to the codec. Each frame will be able to update any of the
available references, but copying between references is not
supported.
Change-Id: I5945b5ce6cc3582c495102b4e7eed4f08c44d5a1
This patch removes the old pred-filter experiment and replaces it
with one that is implemented using the switchable filter framework.
If the pred-filter experiment is enabled, three interopolation
filters are tested during mode selection; the standard 8-tap
interpolation filter, a sharp 8-tap filter and a (new) 8-tap
smoothing filter.
The 6-tap filter code has been preserved for now and if the
enable-6tap experiment is enabled (in addition to the pred-filter
experiment) the original 6-tap filter replaces the new 8-tap smooth
filter in the switchable mode.
The new experiment applies the prediction filter in cases of a
fractional-pel motion vector. Future patches will apply the filter
where the mv is pel-aligned and also to intra predicted blocks.
Change-Id: I08e8cba978f2bbf3019f8413f376b8e2cd85eba4
For coefficients, use int16_t (instead of short); for pixel values in
16-bit intermediates, use uint16_t (instead of unsigned short); for all
others, use uint8_t (instead of unsigned char).
Change-Id: I3619cd9abf106c3742eccc2e2f5e89a62774f7da
Use these, instead of the 4/5-dimensional arrays, to hold statistics,
counts, accumulations and probabilities for coefficient tokens. This
commit also re-allows ENTROPY_STATS to compile.
Change-Id: If441ffac936f52a3af91d8f2922ea8a0ceabdaa5
This adds Debargha's DCT/DWT hybrid and a regular 32x32 DCT, and adds
code all over the place to wrap that in the bitstream/encoder/decoder/RD.
Some implementation notes (these probably need careful review):
- token range is extended by 1 bit, since the value range out of this
transform is [-16384,16383].
- the coefficients coming out of the FDCT are manually scaled back by
1 bit, or else they won't fit in int16_t (they are 17 bits). Because
of this, the RD error scoring does not right-shift the MSE score by
two (unlike for 4x4/8x8/16x16).
- to compensate for this loss in precision, the quantizer is halved
also. This is currently a little hacky.
- FDCT and IDCT is double-only right now. Needs a fixed-point impl.
- There are no default probabilities for the 32x32 transform yet; I'm
simply using the 16x16 luma ones. A future commit will add newly
generated probabilities for all transforms.
- No ADST version. I don't think we'll add one for this level; if an
ADST is desired, transform-size selection can scale back to 16x16
or lower, and use an ADST at that level.
Additional notes specific to Debargha's DWT/DCT hybrid:
- coefficient scale is different for the top/left 16x16 (DCT-over-DWT)
block than for the rest (DWT pixel differences) of the block. Therefore,
RD error scoring isn't easily scalable between coefficient and pixel
domain. Thus, unfortunately, we need to compute the RD distortion in
the pixel domain until we figure out how to scale these appropriately.
Change-Id: I00386f20f35d7fabb19aba94c8162f8aee64ef2b
This commit removed a couple of redundant data structures in frame
coding contextsm, mode_context and mode_context_a, and changed to
use vp9_mode_contexts only. The switch of the context for different
frame type now relies on the switch of frame coding context between
lfc and lfc_a. This commit also removed a number of memcpy among
these redundant data structure.
Change-Id: I42e8174bd60f466b0860afc44c1263896471b0f3
Support for gyp which doesn't support multiple objects in the same
static library having the same basename.
Change-Id: Ib947eefbaf68f8b177a796d23f875ccdfa6bc9dc
